Guidelines for Cement Concrete Mix Design for Pavements (Third Revision)

The Scope of IRC 44 covers specifications and standards for concrete materials and mix design for highway pavements, including high strength and pervious concrete (Clause 1.0). Key aspects include materials testing such as free (surface) moisture content for coarse and fine aggregates (both nil), and sieve analysis for coarse aggregate fractions. The sieve analysis table for coarse aggregate fractions is as follows:

This scope includes definitions, materials, mix design approaches for high strength concrete (Grade M65 and above), and pervious concrete (Clauses 1 to 6). The document also provides abbreviations for cementitious materials and admixtures relevant to highway concrete.

Thus, IRC 44's scope comprehensively addresses materials and mix design parameters for durable highway concrete pavements.

Sources: Clause 1.0, TABLE: Preamble

For Terminology and Definitions in IRC 44, Clause 2.1 states that definitions from IS:456-2000, IS:4845, and IS:6461 (Parts I to IV) apply. Key commonly used terms and their abbreviations include:

These definitions provide a standardized language for concrete materials and mix design in highway concrete guidelines. For detailed definitions, refer to the cited IS codes as per Clause 2.1.

Sources: Clause 2.1

For materials used in cement concrete pavements as per IRC 44, key specifications include the use of Ordinary Portland Cement (OPC), Portland Pozzolana Cement (PPC), and Portland Slag Cement (PSC) as cementitious materials. High Range Water Reducing Agents (HRWRA) and High Range Water Reducing Admixtures (HRWRAS) are used to improve workability and strength. The water-cement ratio (w/c) and water-cementitious material ratio (w/cm) are critical parameters controlling durability and strength. Pavement Quality Concrete (PQC) is specified for the pavement layer. Mix design guidelines cover ordinary and high strength concrete (HSC) including grades M65 and above. Recycled Concrete Aggregate (RCA) and Ready Mix Concrete (RMC) are also referenced. Saturated Surface Dry (SSD) condition is important for aggregate moisture state. These materials and terms are summarized in the provided tables under the "Materials" and "Mix Design" sections of IRC 44.

Sources: Clause 3: Materials, Clause 4: Mix Design, Preamble Tables

The key principles for concrete mix proportioning per IRC 44 include:

• Grade designation: e.g., M65 as per Clause 6.3
• Cement type: OPC 53 grade conforming to IS:269
• Silica fume: Conforming to IS:15388
• Maximum nominal aggregate size: 19 mm
• Minimum cement content: 360 kg/m³
• Maximum water-cementitious materials ratio: 0.40
• Workability: Slump of 25 ± 10 mm
• Degree of supervision: Good
• Aggregate type: Crushed angular
• Chemical admixture: Superplasticizer (Polycarboxylate based)

Material properties for mix design:

Mix adjustments:

• Extra water for dry coarse aggregate absorption (e.g., 6.0 kg/m³)
• Slump adjustments and admixture dosage based on trial mixes (Clause C11)
• For RMC with 1-hour transit, initial slump ~100 mm to achieve 25 mm at placement (Clause C13)

These principles ensure durability, workability, and strength targets are met through trial-based adjustments and adherence to material properties.

Sources: Clause 6.3, Clause 5.3, Clause 4.4, Clause 6.0, Clause C11, Clause C13, Clause D1, Clause D2

The IRC 44 code provides a detailed concrete mix proportioning procedure as per Clauses 5.3, 6.3, and 31.5, including key formulas and tables. The procedure involves:

• Determining the volume of coarse and fine aggregates from Table 11 (Clause 31.5) based on aggregate size and grading zone, adjusted for actual water-cement ratio.
• Calculating absolute volume of concrete as (1 - volume of air), e.g., 0.992 m³ for 0.8% air content.
• Computing volumes of cement, water, and chemical admixture using their masses and specific gravities.
• Calculating volume of total aggregate as the remainder after subtracting cement, water, and admixture volumes from absolute volume.
• Determining mass of coarse and fine aggregates by multiplying their volume fractions, specific gravities, and total aggregate volume.

Example from Clause 31.5 for 31.5 mm aggregate and water-cement ratio 0.32:

This systematic approach ensures correct aggregate proportions and mix volumes for desired concrete quality. Combined grading checks per Table 3 are recommended to optimize aggregate blend.

Sources: Clause 5.3, Clause 6.3, Clause 31.5

Key formulas and specifications for Pervious Concrete Mix Design per IRC 44 are as follows:

• Void Content (Vv) typically around 24% for a percolation rate of 350 mm/min (Clause 2.70, Table 19).
• Paste Volume (Vp) about 11% for 24% void content in well compacted pervious concrete (Clause 2.70, Table 21).
• Coarse Aggregate Volume = 1 - (Void Content + Paste Volume) = 0.65 m³ (Clause 2.70).
• Mass of Coarse Aggregate = Volume of aggregate × Specific Gravity × 1000 (kg/m³) (Clause 2.70).
• Cement Content (c) calculated by: c = [Vp / (0.315 + w/c)] × 1000 kg/m³, where w/c is water-cement ratio (Clause 2.70).
• Water Content (w) and Coarse Aggregate quantities are adjusted based on aggregate moisture condition (SSD, dry, or wet) as per Clause 7.0.

Illustrative mix proportions for M10 grade pervious concrete:

Testing: Water permeability test method is given in Annexure A (Clause 6.3.8).

Adjustments for moisture content in aggregates are detailed in Clause 7.0, including formulas for converting SSD to dry or wet conditions.

This provides a comprehensive framework for pervious concrete mix design ensuring required permeability and strength.

Sources: Clause 2.70, Clause 6.3.8, Clause 7.0

Workability and consistency in IRC 44 are primarily controlled by slump and water content, adjusted through trial mixes and admixture dosage as per Clauses C11 and C13. The target slump is typically 25 ± 10 mm, with adjustments for ready-mix concrete (RMC) to maintain workability over transit time (Clause C13). Water content depends on aggregate size and shape, workability, and admixture use. Table 10 (Clause 4.4.3) provides approximate water content for saturated surface dry aggregates at 50 mm slump for angular aggregates:

Adjustments: reduce water by ~10-20 kg/m³ for less angular aggregates; increase water by ~3% per additional 25 mm slump or use chemical admixtures (superplasticizers) to reduce water demand by 5-20% (Clause 4.4.3). Trial mixes are essential to finalize proportions and ensure durability (Clause C11).

Sources: Clause C11, Clause C13, Clause 4.4.3, Table 10

The target strength for concrete mix proportioning is calculated to ensure that the specified proportion of test results do not fall below the characteristic strength. According to Clause 2.5 and Clause 5.0, the target strength (f') is given by:

f' = f_ck + 1.65 × S

where:

• f_ck = characteristic compressive strength of concrete (N/mm²)
• S = standard deviation of compressive strength (N/mm²)

From Table 6 (Clause 5.0), S = 5.0 N/mm² for general cases. From Table 18 (Clause 2.5), S = 2.5 N/mm² for specific cases.

Clause 6.3.2 reiterates that the mix must be proportioned for this higher target mean strength to maintain quality control.

This approach ensures reliability in concrete strength by accounting for variability in test results during mix design.

Sources: Clause 2.5, Clause 5.0, Clause 5.3.1, Clause 6.3.2

Durability considerations in IRC 44 focus on material properties, mix proportioning, and water permeability testing to ensure long-lasting concrete pavements. Key points include:

• Aggregate Moisture Content: Quantities of coarse and fine aggregates are based on saturated surface dry (SSD) conditions. To convert to dry or wet conditions, adjust aggregate mass and water content using water absorption and moisture content as per Clause 6.3.8.

• Water Permeability Test: Measures infiltration rate (K) of pervious concrete by timing water volume passing through a specimen. The formula is:

  [ K = \frac{W}{A \times t} ]

  where W = volume of infiltrated water (mm³), A = cross-sectional area (mm²), t = time (s).

• Specimen Preparation: Includes curing for minimum 7 days, pre-wetting, wrapping with shrink wrap, and maintaining water head during testing (Clauses A4.1.4 to A4.6).

• Sieve Analysis: Aggregate gradation conforms to specified zones (e.g., Zone II) with detailed % passing for coarse aggregate fractions (Clause 1.0 tables).

These ensure concrete durability by controlling moisture, aggregate quality, and permeability.

Sources: Clause 1.0, Clause 6.3.8, Clause A4.1.4 to A4.6

As per IRC 44 Clause 5.3.9 and 4.5.1, trial mixes are essential to verify calculated concrete mix proportions. The process involves:

• Trial Mix No. 1: Measure workability (slump), observe segregation, bleeding, and finishing.
• If workability differs from the target, adjust water and/or admixture content while maintaining the preselected free water-cement ratio.
• Trial Mix No. 2: Recalculated mix with adjusted water/admixture but same free water-cement ratio.
• Trial Mixes No. 3 & 4: Use same water content as Mix No. 2 but vary free water-cement ratio by ±10%.

These mixes provide data on workability and compressive strength vs. water-cement ratio to finalize proportions. Field trials should replicate actual production methods.

Additionally, mix yield must be checked and adjusted to produce 1 m³ concrete.

For fine and coarse aggregates, moisture corrections are calculated as:

Slump adjustments and admixture dosages are made based on trial results to meet workability and durability requirements (Clause C11, C13).

Sources: Clause 5.3.9, Clause 4.5.1, Clause 4.00, Clause 6.0, Clause C11, Clause C13

IRC 44 provides guidance on the use of admixtures and supplementary materials primarily in Clauses 3.6 and 4.4.3. Per Clause 3.6, mineral admixtures can be added at site as per availability and regulations, with recommended percentage limits subject to specific specifications. Clause 4.4.3 details the selection of water content and chemical admixture (superplasticizer) content, emphasizing factors affecting water demand such as aggregate size, shape, texture, and admixture use. The water content for saturated surface dry aggregates for 50 mm slump and angular coarse aggregate is given in Table 10 as:

Adjustments to water content are recommended based on aggregate shape and workability, with water-reducing admixtures reducing water demand by 5-10% and superplasticizers by 20% or more at appropriate dosages. Trial mixes are essential to finalize water and admixture quantities due to variability in local materials and transport conditions.

Sources: Clause 3.6, Clause 4.4.3, Table 10

Key quality control and testing specifications in IRC 44 include moisture content and sieve analysis for aggregates as per Clause 1.0. For coarse aggregate, free (surface) moisture and absorbed moisture shall be nil. Sieve analysis for coarse aggregate fractions is specified as follows:

For fine aggregate, grading shall conform to Zone II of Table 2 (not fully provided).

These tests ensure material quality and gradation conformity for pavement concrete. Moisture control and sieve analysis are critical for mix design and durability.

Sources: Clause 1.0

For transport and placement of concrete as per IRC 44, key considerations include adjusting initial slump to compensate for slump loss during transit and using chemical admixtures to maintain workability. As per Clause 4.4.3, initial slump should be higher than the required placement slump depending on transport time (e.g., 100 mm initial slump for 25 mm placement slump with 1-hour transit). Water content per cubic meter of concrete depends on nominal maximum aggregate size and is given in Table 10:

Adjustments to water content are made for aggregate shape and workability. Chemical admixtures (superplasticizers) reduce water demand by 5-20% (Clause 4.4.3).

Mix volume calculations (Clauses 4.4.5 and 31.5) include:

• Absolute volume of concrete = 1 - air content
• Volumes of cement, water, admixture calculated from mass and specific gravity
• Volume of aggregates = total volume minus volumes of cement, water, admixture
• Mass of coarse and fine aggregates calculated from their volume fractions and specific gravities

Example for 31.5 mm aggregate size and w/c = 0.32:

These calculations ensure proper mix design for transport and placement with required workability and durability. Trial batches and slump measurements are essential to adjust water and admixture dosages (Clause B11, B13).

Sources: Clause 4.4.3, Table 10, Clause 4.4.5, Clause 31.5, Clause B11, Clause B13

The retrieved context from IRC 44 does not explicitly provide detailed formulas, tables, or specifications specifically for Safety and Environmental Aspects. However, general safety and environmental considerations in highway concrete works typically include proper material handling, dust control, noise management, and waste disposal as per standard construction practices. For concrete mix design and quality control, Tables 5 and 6 provide assumed standard deviations for flexural and compressive strengths respectively, which indirectly support safety by ensuring material reliability (Clause 4.3.3). Key abbreviations related to materials and admixtures are also listed, aiding specification clarity. For comprehensive safety and environmental guidelines, refer to the full IRC 44 document or relevant environmental regulations.

Sources: Clause 4.3.3, Table 5, Table 6

The key references and annexures in IRC 44 include detailed tables and specifications for concrete mix design and material properties. For example, Annexure - A to F provide supplementary data and examples. Important tables include:

• Table 5: Assumed Standard Deviation Values for Mix Designs Based on Flexural Strength, e.g., for 3.5 N/mm² flexural strength, standard deviation is 0.35 N/mm².

• Table 6: Assumed Standard Deviation Values for Mix Designs Based on Compressive Strength, e.g., for M30 grade concrete, standard deviation is 5.0 N/mm², and for M65, it is 6.0 N/mm².

These values apply especially when sufficient test data is unavailable and assume good site control (Clause 4.3.3). Additionally, material test data such as sieve analysis for aggregates is provided (Clause 1.0).

These annexures and tables guide mix proportioning, quality control, and material selection in highway concrete specifications.

Sources: Clause 4.3.3, Table 5, Table 6, Clause 1.0